Record out of Your Amp's FX Loop with an Interface

Alex Kraieski

December 25, 2025 · 7 min read

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The effects loop (FX loop) of an amp lets you route your signal out after the preamp stage (but before the power amp stage) through another signal path of pedals before going back into the amp. Usually, you use it for putting pedals after your preamp, but you can also just record straight out of this into your DAW if you have an interface.

And I think this is a perfect of example of how DAWs, plugins, and modelers don't make tube amps obsolete. I think it all compliments each other as long as you think of it as a modular ecosystem (which has been the point of the electric guitar from the beginning).

Without (unexplained) jargon, here's what I am talking about doing: taking the signal from the FX loop and plugging that into a computer with an audio interface (interface is necessary because guitar cables don't plug directly into usb). Once this signal is in the computer, it gets played through a simulated speaker + microphone that we can choose in software like Logic Pro, Garageband, etc.

How I set it up

My signal chain for this is basically guitar -> front-of-amp pedals -> amp -> fx send -> EQ pedal -> modulation pedals -> delay pedal -> interface -> Cabinet in Archetype Gojira X plugin in DAW.

I am using a Marshall DSL5CR combo amp. Some things will may be different with between amps, but the basic idea is that without disconnecting the speaker, (I think this prevents any avenues of harming your amp, but everything in this article is at-your-own-risk) you run the cable from the last pedal in your FX loop straight into your interface. Also, on my Focusrite Scarlett 2i2, I made sure to deselect "Inst" mode since it is no longer an instrument-level signal. My Focusrite (which is basically entry level btw) still has plenty of headroom for this application.

This wasn't "silent" for me, as there was still a "dry" signal going through the speaker, but I was able to run the amp quieter for this than I ideally would for practicing or recording the speaker with a mic.

In my computer (a Macbook), I use Logic Pro to run amp sims like the Neural DSP line. In this case, we want to use their Archetype Gojira plugin not for its amps, but for the impulse responses (IRs). Each of the 3 amps has a default cabinet matched with it, and you can also choose different microphones.

So when I turn off the amp in the plugin, I get my pedal + Marshall preamp sound through whatever cabinet I select. Pretty neat, I think!

Benefits

Modularity: now my combo and FX loop pedals can be used with a variety of cabs/mics outside of the built in speaker and mics I own
Can blend the mic'd up speaker back in
Bring real tube feel into digital workflows'
Leverages your familiarity with how your physical pedals and amp interact
Try out different cabs without having to physically play the song again and place the mic accurately each time.
The main downsides are that this isn't a silent process (at least on my amp) and that your sound is going to be missing any impact on the response or tone from the power tube. But I'm not enough of an expert to say that's an "invalid guitar tone." One of the big mistakes people can make is to not use an IR, but that's not what we're doing here.

Examples with each cab in the Neural DSP Archetype Gojira Plugin

Sorry for sloppy playing... I broke a string on this take by pulling back too hard with my Floyd at the end, so I hope we can make it do for now. Here's the same crappy take on each cab in the Gojira plugin:

Cab 1:

Cab 2:

Cab 3:

I think all of those are potentially viable amp + cab combos (with more dialing in depending on what you are going for). It could also work blended with a channel with a dynamic mic on the amp. I think cab 2 might get lost in a mix as I had it dialed in for this.

Say what you want about my playing or tone, but it's not the least original tone anyone's done with the Gojira plugin.

Subjectively, it feels like some "Marshall Roar" is missing (compared to the "in-the-room sound" of the combo). I'm not sure if that is because we aren't getting the EL34 power tubes or if what I'm missing is a characteristic of the speaking in my combo.

A low effort take on the proliferation of DAWs and modeling in the guitar world is that it will kill tube amps (or is already killing them). In reality, tube amps have more value than ever because we can remix them into digital recording/production flows in fun ways. You can try out different IRs with your own preamp sound and make your own IRs too. Even if you love recording directly into your interface (without a mic), it seems like owning a tube amp is an asset that expands your arsenal. Unless you want to sound like everyone else.

If you need an interface, Focusrite's Scarlett series is well-regarded at the "entry-level but not junk" price tier. I use the 2i2 (link earns commission), which gives me a couple inputs at my disposal.

Thanks for reading, and always keep experimenting with your sound!